LanzaTech exploring lipids production as part of its CO2 to acetic acid plans; pathways to renewable fuels

17 October 2012

LanzaTech’s proposed gas-to-liquids platform. The products in red would be produced by synthetic biocatalysts, while those in black—ethanol, acetic acid, and 2,3 BDO—can be produced by the LanzaTech native microorganisms. Source: LanzaTech. Click to enlarge.

Earlier this week, LanzaTech announced a partnership with Malaysia’s Petronas to extend the core LanzaTech proprietary CO gas fermentation process to include CO2-containing gases from a variety of sources—including refinery off-gases and natural gas wells—to produce acetic acid, a high-value chemical with applications in the polymers and plastics markets— as well as a possible intermediate for the formation of lipids. (Earlier post.)

In a presentation at the 1st Conference on CO2 as Feedstock, held last week in Essen, Germany, LanzaTech CSO Dr. Sean Simpson described the company’s progress on developing a CO2 pathway. In 2011, LanzaTech announced that it had demonstrated the continuous fermentation of CO2 in the presence of hydrogen to acetic acid, using their modified microorganisms.

CO2 to acetic acid fermentation. Source: LanzaTech. Click to enlarge.

In CO fermentation, explained LanzaTech Communications Director Freya Burton, CO can serve as the carbon and the energy source whereas CO2 can serve only as the carbon source. The hydrogen serves as the energy source in this case.

The development of the CO2 fermentation system leverages LanzaTech’s existing reactor system and gas fermentation knowledge. Petronas, which invested in LanzaTech’s C round (earlier post), is now committed via the new agreement to help work through the technology with LanzaTech. Should the lab and pilot work prove successful and scalable, they will place a demo plant in Malaysia, Burton said.

Part of the challenge is locating sufficient quantities of hydrogen to enable large scale use of the CO2 in waste gases. Another challenge is—assuming successful large scale commercialization is possible—what to do with all the resulting acetic acid.

While acetic acide is a valuable chemical, it is a market that could be saturated quickly, Burton notes. Accordingly, LanzaTech has begun look at the industrial conversion of acetic acid/acetate to lipids, and has demonstrated this. Lipids, in turn, are a proven pathway to jet, diesel and gasoline. (The elucidation of the biochemical pathway from acetic acid to cholesterol—a type of lipid—reaches back to seminal work done by Dr. Konrad Bloch in 1945. Bloch and Feodor Lynen were awarded the 1964 Nobel Prize in Physiology and Medicine for their later discoveries linking acetyl-CoA and fatty acid metabolism.)

LanzaTech envisions using partner technology to convert the acetic acid to lipids—i.e., that conversion wouldn’t actually happen in a LanzaTech bioreactor. The conversion process is being investigated at various institutions and LanzaTech has managed to take acetic acid from its CO2 conversion broth and make an oil. This is now being developed further, says Burton.

Resources

Chemical Sciences Roundtable, Board on Chemical Sciences and Technology, National Research Council. “5. Carbon Dioxide as a Feedstock.” Carbon Management: Implications for R & D in the Chemical Sciences and Technology (A Workshop Report to the Chemical Sciences Roundtable). Washington, DC: The National Academies Press, 2001